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science nutrition <strong>blog</strong>

By; Steve Blechman

400 MG OF Caffeine Is Safe and Harmless

Best Dose for Boosting Exercise Performance!

Caffeine is a stimulant that fitness-minded people know well— as a quick pre-workout that will give your training a buzz. Taken an hour before exercise, caffeine increases alertness, which can make exercise feel less strenuous and enables most athletes to perform better. It’s also a double-edged sword, as it’s often blamed for sleeplessness, anxiety and frequent trips to the bathroom. It turns out that those who have ridiculed caffeine or think it’s harmful have beans in their head. A new study shows that caffeine is safe even for pregnant women and young children, and it boosts physical and mental performance. When taken at the recommended daily amount of 400 milligrams— about four cups of coffee or eight cups of tea— caffeine has no lasting damage on the body.

A review of 44 trials, published in the journal Complete Nutrition and conducted by Dr. Carrie Ruxton, Ph.D., RD, a leading British dietitian who has advised the European Food Safety Authority, threw a monkey wrench into the mixed research that has warned consumers about the potential dangers of caffeine consumption. A separate review conducted by the International Life Sciences Institute (ILSI) found that 400 milligrams of caffeine is safe on a daily basis. Researchers at the ILSI examined over 740 studies about the effects of caffeine on humans to make the claim.                             

Ruxton, who was the driving force behind the myth-busting review in Complete Nutrition, described caffeine as “one of the most polarizing dietary substances around,” and argued that evidence proves the drug is safe— despite the “bad rap” it gets in the media. She told MailOnline: “Unfortunately, there is an enormous amount of myth and misinformation surrounding caffeine. The reality is that people who cut out tea and coffee may miss out on the potential health benefits of the compounds they contain.”

Ruxton’s review examined at least 15 different trials that documented the benefits caffeine has on the brain, including improving reaction times, accuracy in tests and alertness. Such studies also hinted that it influences the release of dopamine, which is thought to enhance mood and prevent the blues. Another 29 randomized, controlled trials that were assessed confirmed caffeine enhances sports performance. The researchers estimate that three out of four elite athletes use caffeine supplements to boost their performance.

The review published in Complete Nutrition supports another study recently published in The Journal of Applied Physiology that found acute caffeine supplementation can improve performance. Because there are concerns that caffeine users may become habituated to its effects— and one cup in the morning turns to three cups by the end of the day— athletes have typically been advised to stop drinking coffee or anything containing caffeine for about a week before competition. But Bruno Gualano, a professor of physiology and nutrition at the University of São Paulo in Brazil, found that regardless of habitual caffeine intake in one’s diet, caffeine can enhance your training.

In Gualano’s study, competitive male cyclists consumed 400 milligrams of caffeine one hour before a ride, which is equivalent to the amount of caffeine in four cups of coffee. The subjects also received a placebo before another ride. Almost all of the riders were able to pedal harder and faster after swallowing the caffeine pill— 3.3 percent faster on average compared to when they had no pill, and 2.2 percent faster than when they took a placebo. Cyclists who usually drank large amounts of coffee or caffeine drinks every day received the same boost from caffeine as light coffee drinkers. Gualano’s study refutes previous advice from some scientists and coaches that in order to gain any performance boost from taking caffeine before a workout, you have to abstain from coffee or caffeine for a few days or weeks.

You can get your caffeine fix of 400 milligrams per day (maximum) in four cups of coffee, eight cups of tea, five cans of the energy drink Red Bull or one serving of AML Preworkout from Advanced Molecular Labs. (Journal of Applied Physiology)

The Antagonistic Effects of Caffeine and Taurine

In 2013, worldwide sales of energy drinks exceeded $50 billion. The principal ingredients of these beverages are typically caffeine, taurine and usually high fructose corn syrup. A study from Colombia found that identically tasting beverages containing either caffeine (80 milligrams), taurine (1,000 milligrams), a combination of caffeine and taurine, or a commercial energy drink (Red Bull) had no effect on cardiorespiratory fitness, endurance, strength, power or cognitive ability. Combining caffeine with taurine has antagonistic effects. For best performance results, skip the taurine in your energy or pre-workout drink. (Journal International Society Sports Nutrition)

Meta-Analysis Update

Branched-Chain Amino Acids Promote Recovery

Best Taken After Exercise – Not Before or During

Leucine, isoleucine and valine are called branched-chain amino acids (BCAAs). They are essential amino acids, which means they must be consumed in the diet. BCAAs are involved in protein synthesis, tissue repair, signaling a biochemical pathway essential for muscle protein synthesis (i.e., mTOR) and blood sugar control. A meta-analysis that combined the results of seven studies showed that BCAA supplements are best taken after exercise— not before or during exercise (intra-workout). The studies revealed that BCAAs taken during exercise “is not effective on muscle soreness at follow-up time,” the researchers wrote.

Leucine consumption before your workout promotes sluggishness and fatigue. Recent research has shown that leucine competitively inhibits dopamine precursor tyrosine into the brain, and reduces dopamine levels. Dopamine and noradrenaline are the “flight-or-fight” hormones that allow the body to perform at higher levels than normal. Increasing dopamine reduces fatigue and increases mental arousal, focus, confidence and greater levels of motivation. Pre-workout leucine and BCAA consumption is not the best for optimal muscular performance.

According to the meta-analysis, when BCAAs are taken after exercise, they reduce post-exercise muscle soreness and creatine kinase— a marker of muscle damage— better than rest alone.

 BCAAs promote recovery by stimulating the mTOR pathway to increase protein synthesis to repair injured tissue. Leucine, one of the BCAAs, is the most important chemical that turns on the mTOR pathway, so it is likely that consuming leucine after exercise would be just as effective or more effective (and cheaper) than consuming BCAAs. The addition of isoleucine and valine may hinder the benefits of leucine due to competition for transport into muscle cells. The BCAAs share the same active transport system into cells and muscle cells. (Nutrition)

ATP Supplement Prevents Fatigue During Interval Training

 Oral adenosine triphosphate (ATP) supplements prevented declines in ATP and boosted power output, compared to a placebo (fake ATP), during repeated six-second sprints on a stationary bike. Martin Purpura from Increnovo LLC, and colleagues, gave either 400 milligrams of ATP or a placebo daily for two weeks, before the exercise test. Adenosine triphosphate is called the “energy currency of the cell” because it supplies energy for most cellular chemical reactions. Oral ATP supplements might prevent fatigue by improving cellular energy regulation.

Most ATP is found within the cells, and is critical for fueling muscle contractions and the majority of cell functions. Very little oral ATP enters the bloodstream intact. Instead, ATP breakdown products such as purines bind to cell receptors that influence muscle blood flow, learning movement skills, food intake and sleep. Oral ATP supplements likely increase muscle endurance by enhancing muscle blood flow during intense, prolonged muscle contractions.

Creatine monohydrate is superior to ATP for increasing intracellular ATP levels. Creatine supplies phosphates for ATP synthesis inside the cells, while oral ATP supplements influence cell signaling outside the cells. ATP and creatine monohydrate are effective ergogenic aids, but they work by different mechanisms. (Journal American College of Nutrition)

Taurine Has No Effect on High-Intensity Endurance Performance

Taurine does not improve high-intensity running performance— according to a Brazilian study. Taurine is an amino acid that helps regulate cell fluid balance and calcium levels, protects cells against reactive oxygen species, stabilizes cell membranes and decreases inflammation. It is found in high concentrations in nerve and muscle cells. It is also a prominent ingredient in many energy drinks and bodybuilding supplements. It crosses the blood-brain barrier and is involved in a variety of brain functions. However, few studies have examined its effectiveness in improving athletic performance. Taurine provides some protection against blood clotting from taking anabolic steroids, but does not improve exercise performance. (Applied Physiology, Nutrition and Metabolism)

 Agmatine Nerve Protector – No Performance Benefits?

A company called Gilad&Gilad has filed a patent for using agmatine in dietary supplements, nutraceuticals and foods. Agmatine is a breakdown product of the amino acid arginine. Limited research has shown that the chemical protects nerve cells from metabolic damage (Pain Medicine, 11: 356-368, 2010). A small study published in 2010 got the attention of some bodybuilders who started using it as a supplement. There are zero studies in the published literature on the ability of agmatine to help nitric oxide production, aid in recovery or improve metabolic function. In fact, rodent studies show that agmatine may inhibit nitric oxide in tissues. Gad Gilad, CEO of Gilad&Gilad, said that there is no evidence that the supplement helps bodybuilders improve performance. “That agmatine is touted for bodybuilding is completely unsubstantiated and is backed by outright false claims,” Gilad said. (NUTRAingredients-usa.com)

Citrulline for Health and Performance

A review of literature by Arturo Figueroa from Florida State University, and colleagues, concluded that L-citrulline and watermelon reduces resting blood pressure— and chronic use may increase endurance. Citrulline is an important amino acid involved in the formation of urea. It is a popular component in athletic food supplements because it participates in key amino acid reactions and influences blood flow by increasing nitric oxide levels. Nitric oxide is an important chemical secreted by the inner lining of the blood vessels, which controls blood flow throughout the body. Nitric oxide is vital for muscle blood flow, sexual function, fuel and hormone delivery to muscles, tissue oxygenation and general energy levels. Other studies found that citrulline increases brown fat activity, which increases caloric expenditure and promotes fat burning. Citrulline increased levels of hormone-sensitive lipase by 150 percent, which promoted fat mobilization and use. Citrulline is an underappreciated supplement that improves fat burning and muscle blood flow, and protects the gut from injury during exercise. (Current Opinion in Clinical Nutrition & Metabolic Care)

Beta-Alanine Promotes Muscle Relaxation and Prevents Fatigue

High-intensity exercise increases hydrogen ion, inorganic phosphate and adenosine diphosphate that slow biochemical reactions and promote fatigue. Buffers, such as bicarbonate and carnosine, can help neutralize these chemicals and promote performance. Carnosine, which is made from alanine, is an important antioxidant that protects cells from destruction and buffers acids that cause fatigue. A study led by Rebecca Jones from Nottingham Trent University in the U.K. found that beta-alanine supplements promoted muscle relaxation, which is critical during short, repeated high-intensity contractions. Muscle carnosine levels are highly related to maximum exercise capacity. Supplementing alanine increases muscle carnosine levels, which enhances muscle-buffering capacity and prevents fatigue. (European Journal of Applied Physiology)

ATP Supplements Promote Recovery From High-Intensity Exercise

Recovery from repeated bouts of high-intensity exercise, such as football, soccer, tennis, weight training and interval training, depends on restoration of adenosine triphosphate (ATP) in muscles. ATP is the body’s “energy currency” that participates in muscle contractions, electrical impulses in nerves and muscles, and the synthesis and breakdown of fuels and tissues. Martin Purpura from Increnovo LLC in Milwaukie, Wisconsin found that oral ATP supplements (400 milligrams per day for 14 days) prevented depletion of ATP after intense exercise and increased peak power output. Oral ATP supplements might prevent fatigue by improving cellular energy regulation. Oral ATP supplements likely increase muscle endurance by enhancing muscle blood flow during intense, prolonged muscle contractions. (Journal of the American College of Nutrition)

Citrulline Malate Improves Strength and Power

Citrulline malate (8 grams) increased grip strength, vertical jump and cycling power output in female masters tennis players— according to a study led by Jordan Glenn from Louisiana Tech University in Ruston, Louisiana. Citrulline is an amino acid that is converted to arginine, which increases levels of nitric oxide— an important chemical that regulates blood flow throughout the body. Citrulline also increases brown fat activity, which increases caloric expenditure and promotes fat burning. It does this without stimulating the sympathetic nervous system, which avoids increases in heart rate, blood pressure and anxiety levels. Citrulline malate might be an effective supplement for athletes. Citrulline malate is best when taken with other nitric oxide activators such as grape skin polyphenols and folic acid. Folic acid functions as a co-factor for the enzyme dihydrofolate reductase, which synthesizes tetrahydrobiopterin (BH4). Oral folic acid can improve nitric oxide production and vasodilation. (European Journal of Sports Science)

Beta-Alanine Increases Endurance and Strength

High-intensity exercise increases chemicals such as hydrogen ion, inorganic phosphate and adenosine diphosphate that slow biochemical reactions and promote fatigue. Buffers, such as bicarbonate and carnosine, can help neutralize these chemicals and promote performance. Carnosine, which is made from alanine, is an important antioxidant that protects cells from destruction and buffers acids that cause fatigue. Muscle carnosine levels are highly related to maximum exercise capacity. Supplementing carnosine or alanine increases muscle carnosine levels, which enhances muscle-buffering capacity. Muscle carnosine levels decrease with age, which reduces the capacity for high-intensity exercise. Jordan Glenn from the University of Arkansas, and co-workers, found that supplementing beta-alanine for 28 days in female masters athletes increased lower body muscle strength and exercise capacity, compared to a placebo (fake alanine). Beta-alanine is an effective supplement for intensely training, older female athletes. (Journal Strength Conditioning Research)

NAC Interferes With Cellular Responses to Endurance Training

N-Acetyl-Cysteine or acetylcysteine (NAC) is a natural amino acid byproduct found naturally in foods that fight free radicals, and it improves metabolic health. Physicians often use it to break up mucus accumulation in the lungs in conditions such as emphysema, pneumonia, bronchitis and tuberculosis. It is also used to treat toxic overdoses of acetaminophen— the most common cause of poisoning in the United States. NAC works together with glutathione to help rid the body of toxic chemicals. Recent studies on muscle growth found that suppressing free radicals and blocking inflammation with non-steroidal anti-inflammatory drugs, ice therapy or antioxidants interferes with the adaptation to training. Exercise increases cell structures called mitochondria. Rats given NAC did not respond normally to endurance training. In other words, the supplement had a negative effect on performance. (Free Radical Biology and Medicine)

Creatine Plus Caffeine Improves Endurance

Creatine monohydrate improves power output and speeds recovery from intense training. Caffeine also increases power, strength and promotes endurance. The combination of creatine plus caffeine increases performance more than creatine alone. A study from Taiwan found that a single dose of caffeine (6 milligrams per kilogram of bodyweight) increased endurance output during a maximum test on a stationary bike, in test subjects who had consumed creatine monohydrate for five days (0.3 grams per kilogram of bodyweight per day). The supplements had no effect on maximal oxygen consumption but they increased exercise capacity. Athletes can benefit from the combination of creatine and caffeine during training cycles. (European Journal Sports Science, 12:338-346)

Beetroot Juice Reduces Muscle Soreness

Beetroot juice is a superfood. More than 50 studies have shown that beetroot juice enhances blood vessel health, improves endurance, boosts oxygen delivery, reduces the work of the heart during exercise and helps control blood pressure. A study led by Tom Clifford from Northumbria University in the U.K. found that beetroot juice decreased muscle soreness and promoted recovery in the vertical jump following high-intensity eccentric exercise (100-drop jumps). Eccentric exercise, which involves lengthening muscle contractions, is linked to muscle soreness and post-exercise inflammation. The test subjects drank either an eight-ounce or four-ounce glass of beetroot juice or placebo (fake beetroot) immediately after exercise, and 24 and 48 hours during recovery. High doses of beetroot juice reduced muscle soreness and prevented deterioration in jumping performance, compared to the placebo. Delayed onset muscle soreness is caused by small injuries to the muscle cells, and further damage triggered by inflammation. Beetroot works by decreasing inflammation. (European Journal of Applied Physiology)

Betaine Is an Effective Supplement

Betaine or trimethylglycine is an amino acid compound found in wheat, spinach, shellfish and sugar beets. Research has shown that it increases strength, power and muscle growth. It is an important regulator of body water and is useful in reducing levels of an inflammatory chemical called homocysteine, which is an important risk factor for coronary artery disease. Ranchers use betaine to increase muscle mass in domestic animals. It assists glutathione with detoxification reactions in the liver. It is also useful for preventing depression. A literature review led by Christopher Day from the Laboratory of Receptor Biology and Gene Expression, at the National Cancer Institute’s Center for Cancer Research in Bethesda, Maryland concluded that betaine is an effective supplement for combating fatty liver disease. Betaine is an important human nutrient that is rapidly absorbed and used as a fluid regulator, and participates in amino acid reactions that help maintain liver, heart and kidney health. Betaine reduces blood levels of homocysteine and can improve athletic performance. (Biochimica et Biophysica Acta)

Beetroot Extract Improves Neuromuscular Efficiency During Weight Training

Beetroot juice is high in nitrates that are important for synthesizing nitric oxide in the inner lining of the blood vessels. It is particularly effective in promoting blood vessel health. Beetroot juice increases brain blood flow, which enhances cognitive function and neuromuscular control. Sean Flanagan and co-workers from the Ohio State University found that supplementing beetroot extract for three days improved neuromuscular function before, during and after an intense weight-training workout, compared to a placebo (fake beetroot). Motor unit firing rates were lower at the onset of exercise, and continued as the muscles fatigued. This showed that the supplement promoted neuromuscular control during fatiguing exercise. Motor units are nerve-muscle combinations that control movements during sports. (Journal American College of Nutrition)

NAC Might Impair Nitric Oxide Metabolism

NAC (N-acetylcysteine) is an amino acid derived from L-cysteine, and found in dietary supplements that fight free radicals. Free radicals are highly reactive chemicals produced naturally during metabolism. Excessive and chronic elevations of free radicals break down cell membranes, destroy DNA, trigger muscle soreness and protein breakdown, impair the capacity of the immune system and lead to cardiovascular disease. Physicians often use NAC to break up mucus accumulation in the lungs in conditions such as emphysema, pneumonia, bronchitis and tuberculosis. However, a German study from Hannover Medical School found that NAC might interfere with absorption of nitrite in the kidneys, which could have a negative effect on nitric oxide metabolism— an important chemical for tissue blood flow. NAC helps buffer the effect of excessive free radical accumulation, but it could interfere with nitric oxide metabolism. Avoid pre-workout antioxidant supplements such as NAC, taurine, vitamin C and vitamin E to assure maximum performance and exercise adaptation. (International Journal Of Cardiology)

Citrulline Prevents Gut Injury During Exercise

Citrulline is an amino acid that is converted to arginine, which increases levels of nitric oxide— an important chemical that regulates blood flow throughout the body. A study led by Kim van Wijck from the Netherlands showed that supplementing with 10 grams of citrulline before a one-hour bike ride at 70 percent of maximum effort protected the gut from injury and increased blood flow to the spleen, compared to a placebo (fake citrulline). The spleen is an important blood reservoir that increases blood volume during exercise. Other studies found that citrulline increases brown fat activity, which increases caloric expenditure and promotes fat burning. Citrulline increased levels of hormone-sensitive lipase by 150 percent, which promoted fat mobilization and use. Citrulline is an underappreciated supplement that improves fat burning and muscle blood flow, and protects the gut from injury during exercise. (Medicine Science Sports Exercise)

Vitamins C and E Supplements Interfere With Strength-Training Gains

Bodybuilders often take vitamins C and E supplements to prevent illnesses, such as the common cold, to promote connective tissue repair after intense training, and to protect soft tissue against free radical damage. A study led by Gøran Paulsen from the Norwegian School of Sports Scientists concluded that high doses of vitamins C and E (1,000 milligrams per day for C and 235 milligrams per day for E) interfered with training-induced muscle growth and strength gains. Vitamins C and E are powerful antioxidants that reduce free radicals— highly reactive chemicals produced naturally during metabolism. Excessive levels have been linked to cell damage, suppression of the immune system and premature death. However, these chemicals also promote adaptation to exercise stress. Some oxidative stress is good, while excessive oxidative stress is harmful. Athletes should strive to get vitamins C and E through the diet in foods such as oranges, vegetables and plant oils, and avoid high-dose supplements. (Journal of Physiology)

Beta-Alanine Plus Creatine Increases Power Output and Prevents Fatigue

Creatine monohydrate and beta-alanine increased power output and slowed the onset of fatigue during repeated Wingate tests (30-second maximum sprints on a stationary bike)— according to a Turkish study. Creatine monohydrate improves exercise performance, particularly during weight training and high-intensity interval training. Alanine and carnosine are important chemicals found in muscle that affect strength, muscle size and metabolism. Alanine is an amino acid that provides energy during exercise and prevents neuromuscular fatigue by increasing tissue carnosine levels. Carnosine is a dipeptide (combination of two amino acids) found in meat that is composed of the amino acids alanine and histidine. It is critical for protein synthesis and breakdown, and may help prevent nerve degeneration and diabetes. Supplementing the diet with beta-alanine and creatine monohydrate for 22 days for one month increased high-intensity exercise capacity more than a placebo (fake supplements). (Journal Sports Medicine Physical Fitness)

Tyrosine Promotes Deep Thoughts

Back where I come from, we have universities— seats of great learning, where men go to become great thinkers. And when they come out, they think deep thoughts and with no more brains than you have. But they have one thing you haven’t got: tyrosine supplements. Dutch researchers found that consuming supplemental tyrosine increased the capacity for deep thoughts (concentration) but had no effect on creativity. Tyrosine is a precursor to dopamine, a brain chemical that controls thought processes. Test subjects took a single dose of either two grams of L-tyrosine or placebo (fake tyrosine) before performing a series of mental tasks. Tyrosine improved concentration, and could be an important supplement for athletes, students and magazine writers. (Psychological Research)

Creatine Increases Muscle Power

Creatine monohydrate is an effective performance-enhancing substance that increases muscle power and recovery from repeated bouts of high-intensity exercise. It promotes performance in sports such as track and field, football, bodybuilding, tennis and weightlifting. While the supplement is widely used by high school athletes, its effectiveness or safety are not known. Researchers from Chile found that elite junior soccer players improved power output after consuming creatine monohydrate for two weeks. This was a small study involving only nine subjects in the experimental group. Also, the athletes experienced only minimal improvements in performance. We know little about the safety of this supplement in young athletes, so at this time we can’t recommend it. (Journal International Society Sports Nutrition)

ATP Supplement Prevents Fatigue During Interval Training

Oral adenosine triphosphate (ATP) supplements prevented declines in ATP and boosted power output, compared to a placebo (fake ATP), during repeated six-second sprints on a stationary bike. Martin Purpura from Increnovo LLC, and colleagues, gave either 400 milligrams of ATP or a placebo daily for two weeks, before the exercise test. Adenosine triphosphate is called the “energy currency of the cell” because it supplies energy for most cellular chemical reactions. Oral ATP supplements might prevent fatigue by improving cellular energy regulation.

Most ATP is found within the cells, and is critical for fueling muscle contractions and the majority of cell functions. Very little oral ATP enters the bloodstream intact. Instead, ATP breakdown products such as purines bind to cell receptors that influence muscle blood flow, learning movement skills, food intake and sleep. Oral ATP supplements likely increase muscle endurance by enhancing muscle blood flow during intense, prolonged muscle contractions.

Creatine monohydrate is superior to ATP for increasing intracellular ATP levels. Creatine supplies phosphates for ATP synthesis inside the cells, while oral ATP supplements influence cell signaling outside the cells. ATP and creatine monohydrate are effective ergogenic aids, but they work by different mechanisms. (Journal American College of Nutrition)

Do Ketones Improve Performance?

During the Olympics, the media reported that some cyclists were supplementing ketones to improve performance. Ketones produced naturally during metabolism cause euphoria. Cyclists consume ketones supplements to delay fatigue. The brain uses mainly glucose (sugar) for fuel but it can also use ketones— such as acetone, acetoacetate and beta-hydroxybutyrate. During low-calorie dieting, the body produces ketones to supply fuels to the brain. A literature review by researchers from Maastricht University led by Philippe Pinckaers concluded that supplementing ketones has no effect on physical performance. The results are predictable because the breakdown of ketones releases energy more slowly than carbohydrates. (Sports Medicine)

Nitrate Supplements Improve Muscle Contraction

Nitrate supplements, which increase nitric oxide levels, improve cardiovascular function at rest and energy metabolism during exercise. Nitric oxide is a gas released by the inner lining of blood vessels that is critical for regulating blood flow and blood pressure. Georg Haider and Jonathan Folland from Loughborough University in the U.K. found that supplementing nitrates (beetroot juice) for seven days improved the contractile capacity of muscle in untrained people. It did not increase maximum strength and power, but the muscle changes could be beneficial in endurance exercise. Foods and supplements that increase nitric oxide production, such as L-arginine, beetroot extract and hawthorn berries increase muscle blood flow. This could increase the delivery of nutrients during and after exercise, which could improve performance and promote recovery. Nitrate supplements might improve endurance performance by increasing efficiency, increasing tissue blood flow, and improving muscle contractile capacity. (Medicine Science Sports Exercise)

The Antagonistic Effects of Caffeine and Taurine

In 2013, worldwide sales of energy drinks exceeded $50 billion. The principal ingredients of these beverages are typically caffeine, taurine and usually high fructose corn syrup. A study from Colombia found that identically tasting beverages containing either caffeine (80 milligrams), taurine (1,000 milligrams), a combination of caffeine and taurine, or a commercial energy drink (Red Bull) had no effect on cardiorespiratory fitness, endurance, strength, power or cognitive ability. Combining caffeine with taurine has antagonistic effects. For best performance results, skip the taurine in your energy or pre-workout drink. (Journal International Society Sports Nutrition)

Beta-Alanine Is an Effective Sports Supplement

Alanine is an amino acid that helps supply energy during exercise. It is converted to blood sugar in the liver by a process called the glucose-alanine cycle. While it is not used to synthesize muscle tissue or enzymes, it influences exercise capacity— particularly endurance performance. The International Society of Sports Nutrition, in a position statement, concluded that alanine increases muscle carnosine levels and acts as an intracellular buffer. Alanine is a safe supplement with few side effects. It improves exercise performance in exercise lasting one to four minutes. It reduces fatigue in older people, and may be particularly beneficial when consumed with other supplements such as creatine monohydrate. (Journal International Society Sports Nutrition)

L-Citrulline Improves Performance

Citrulline is an important amino acid involved in the formation of urea. It is a popular component in athletic food supplements because it participates in key amino acid reactions and influences blood flow by increasing nitric oxide levels. Nitric oxide is an important chemical secreted by the endothelium— the inner lining of the blood vessels. Stephen Bailey and colleagues from Exeter University in the United Kingdom found that citrulline supplements (six grams per day) improved resting blood pressure, accelerated oxygen uptake during exercise, improved endurance performance and enhanced tolerance to high-intensity exercise in healthy adults. Watermelon rind is an excellent source of citrulline. (Journal Applied Physiology)

Tyrosine Increases Mental Function During Heat Exposure

Several months ago, we reported studies showing that supplementing the amino acid tyrosine improved concentration. Tyrosine is a precursor to dopamine, a brain chemical that controls thought processes. A study from the United Kingdom showed that tyrosine supplements improved mental effort and vigilance in soccer players subjected to a 90-minute simulated match in the heat. Many researchers believe that central nervous system fatigue is an important reason that performance decreases in athletes during prolonged exercise. Tyrosine may improve mental function during intense training and competition. Tyrosine is best taken with other dopamine activators such as caffeine, Mucuna pruriens seed extract rich in L-dopa, and folic acid. Folic acid increases dopamine by increasing tetrahydrobiopterin (BH4) levels. As a co-factor for tyrosine hydroxylase, BH4 facilitates the conversion of tyrosine to L-dopa, which is a precursor to dopamine. (European Journal of Applied Physiology)

Excessive Antioxidant Consumption May Slow Training Gains

Antioxidants are chemicals such as vitamin C and vitamin E that reduce the effects of free radicals (reactive oxygen species) that damage tissues, promote muscle soreness and speed fatigue. Consuming antioxidant supplements has been a natural nutrition fad for more than 30 years. Many popular foods contain added antioxidants to boost their sales. However, many recent studies found that high antioxidant supplement consumption in the diet suppresses muscle protein synthesis, and can reduce the positive effects of exercise training. An article by Laura Beil concluded that athletes are better off getting their antioxidants from natural foods found in fruits, vegetables and grains, rather than from supplements. (Science News)

Citrulline Promotes Abdominal Fat Loss

Citrulline is an amino acid that promotes protein synthesis and fat loss. A French study from Paris Descartes University on overweight rats fed high-fat diets found that supplementing citrulline reduced blood sugar production in the liver, and triggered abdominal fat loss. Citrulline increases brown fat activity, which increases caloric expenditure and promotes fat burning. Brown fat is a highly thermogenic tissue that dissipates energy as heat instead of storing it as fat. Citrulline increased levels of hormone-sensitive lipase by 150 percent, which also promoted fat mobilization and use. (Molecular Nutrition Food Research)

Magnesium Supplements Reduce Blood Pressure and Boost Testosterone and Nitric Oxide

Hypertension (high blood pressure) is linked to coronary artery disease and kidney failure. Major risk factors include smoking, physical inactivity and high salt intake. Inadequate intake of magnesium may be a factor because of the mineral’s effect in reducing stress on the heart muscle. British researchers found that short-term administration of 300 milligram per day was linked to a three to four millimeters of mercury decreases in systolic and diastolic blood pressure (higher and lower blood pressure numbers) following intense exercise. Magnesium lowers blood pressure by raising nitric oxide levels. Magnesium is best taken with potassium before exercise. The best forms of magnesium and potassium are from potassium and magnesium citrate. Studies have also shown that magnesium supplements boost testosterone. (Journal International Society Sports Nutrition)

Beetroot Juice Improves Performance and Cardiovascular Function

Beetroot juice improves endurance capacity, boosts oxygen delivery and reduces the work of the heart during exercise— according to researchers from Korea and the University of California, Davis. College-aged males were fed beetroot juice or nitrate-depleted beetroot juice for 15 days. Beetroot juice doubled blood nitric oxide, a critical chemical for controlling blood flow. Beetroot juice reduced systolic blood pressure, diastolic blood pressure, mean arterial pressure and total peripheral resistance at rest and during exercise. It also lowered the load on the heart during exercise, as measured by rate-pressure product (heart rate times systolic blood pressure). Beetroot juice is an important supplement for improving cardiovascular health and enhancing endurance capacity. Other studies have found that a single glass of beetroot juice increased performance in kayaking and cycling. (American Journal of Physiology Regulatory, Integrative and Comparative Physiology)

Beetroot Juice Improves Performance

Beetroot is high in nitrates that stimulate the inner lining of blood vessels to secrete nitric oxide, a chemical that controls blood flow. Researchers from the University of Western Australia found that a single dose of beetroot juice improved exercise performance in a 500-meter kayak time trial, and during an exercise test performed in the laboratory on a kayak ergometer. Beetroot also improved paddling efficiency. Beetroot is an effective performance-enhancing supplement that would be helpful for endurance athletes during practice or competition. (International Journal Sports Nutrition Exercise Metabolism)

Citrulline Increases Abdominal Fat Burning

A French study on old rats led by Christophe Moinard from the University Paris Descartes showed that supplementing citrulline reduced abdominal fat levels and protected against age-related cell destruction. Citrulline is an amino acid that is converted to arginine, which increases levels of nitric oxide— an important chemical that regulates blood flow throughout the body. Citrulline also increases brown fat activity, which increases caloric expenditure and promotes fat burning. It does this without stimulating the sympathetic nervous system, which avoids increases in heart rate, blood pressure and anxiety. Citrulline increased levels of hormone-sensitive lipase by 150 percent, which promoted fat mobilization and use. Citrulline is an underappreciated supplement that improves fat burning and muscle blood flow. (Journal of Nutrition)